Cylinder liner for a cylinder crankcase

ABSTRACT

A cylinder liner ( 2 ) for a cylinder block has a contouring ( 6 ) at one end. The contouring ( 6 ) serves to support the liner ( 2 ) on a sleeve ( 4 ) inside a die-casting tool. When the liner ( 2 ) is cast in, recesses ( 10 ) of the liner ( 2 ) are filled by the material of the cylinder crankcase whereby preventing the liner ( 2 ) from seating toward an oil chamber ( 14 ). The invention also relates to a method for producing a cylinder liner of the aforementioned type.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national stage of PCT/EP2003/008971 filed Aug. 13,2003 and based upon DE 102 38 873 filed Aug. 24, 2002 under theInternational Convention.

FIELD OF THE INVENTON

The invention concerns a cylinder sleeve as well as a process forproducing a cylinder sleeve.

RELATED ART OF THE INVENTION

Cylinder crank cases, in particular those for light metal motors, arefrequently reinforced locally in the area of the cylinder runningsurfaces by a cylinder liner. Cast in cylinder liners generally extendthrough the so-called cylinder space from the crank case to the cylinderhead separation plane.

Due to high pressures during the operation of the motor there maysometimes be caused a displacement of the cast in cylinder liner in thedirection of the crank shaft housing. This is referred to as settling ofthe liner. The settling can be prevented in comparatively complex andlabor intensive manner by casting technical methods or by surfacetreatment of the liner.

SUMMARY OF THE INVENTION

The task of the invention is comprised therein, of providing aneconomical device and method, in order to prevent the settling of thecylinder liner.

The task is solved by a cylinder sleeve for a cylinder crank case,thereby characterized, that the cylinder sleeve (2) includes on one end(5) a contouring (6), wherein at least one highest rise (8) of thecontouring (6) supports the cylinder sleeve (2) in a pressure injectioncasting tool against a center sleeve (4) as well as a process forproducing a cylinder sleeve, wherein multiple sleeves (2, 3) are dividedout from a tube (20), thereby characterized, that by one cutting tool(22) an axial movement is described relative to the tube (20) and thetube (20) is moved circumferentially.

The inventive cylinder liner has a contouring on one end. The contouringbrings about a supporting of the cylinder liner on a (center) sleeveinside a die casting tool in the manner that at least one highestelevation of the cylinder liner lies against a tool edge of the sleeve.This edge forms for its part in the cylinder sleeve the boundary of thecylinder tube to the crank shaft housing.

Recesses in the contour of the cylinder liner are filled by a metal ofthe cylinder block (cast in). In the area of the recesses of thecontouring a cylinder running surface is formed by the crank case orcylinder block metal.

The filling of the contouring by the cast around material has theconsequence that the cylinder liner is supported and therewith an axialmovement of the cylinder liner in the direction of the crank case isprevented. Besides this, by the contouring a saving in cylinder linermaterial is achieved, which as a rule is move expensive than thematerial of the material of the casting.

The cylinder liners are in general divided out of a long tube. In thiscase the material savings in cylinder liners can be substantiallyincreased, when the contouring of one cylinder liner forms the negativeimage of the contouring of a further, corresponding cylinder liner. Thematerial savings can herein be per cylinder liner one half of themaximal contour depth.

For the further optimization of material saving it is further useful,that the contour for each cylinder liner exhibits a periodic symmetry.As a consequence it is then likewise useful, that the correspondingcylinder liner exhibits the same, however phase shifted periodicsymmetry.

Since the material saving depends upon the depth of the contouring, itis useful, to utilize the maximal depth available under operatingconditions. For this the bottom dead center (direction changing point)of the lower piston ring has been found useful as the border of thecontouring. Below this direction changing point the tribologicrequirements of the cylinder contact surface is comparative low, so thatno disadvantage results, when in this area the cylinder contact surfaceis partially formed by casting material.

A further component of the invention is a process for production of acylinder liner. The inventive process, in which cylinder liners aredivided out of a single tube, characterizes itself thereby, that acutting tool describes with regard to the pipe one axial movement, incomparison, to which the pipe itself is circumferentially or rotatingmoved.

By a suitable control there is thus the material saving cutting out ofthe inventive cylinder liners made possible. In comparison to aconventional saw cut therewith 3 mm to 4 mm material can be saved.

In a preferred embodiment the cylinder liners are separated from insidetowards outside. Thereby it is prevented, without requiring follow-upworking, that a burr remains in the inner area of the cylinder liner.

As cutting processes there come into consideration water jet cutting,laser cutting, roll separating, precision cutting or precision stamping.A further advantageous process is the so-called stamp cracking, which isbased upon precision cutting, in which however the cutting process issupported by an axial counter force.

BRIEF DESCRIPTION OF THE DRAWING

Advantageous embodiments of the invention are described in greaterdetail on the basis of the following figures and the process examples.

Therein there are shown:

FIG. 1 a cylinder liner with contouring on a center sleeve in a pressuredie casting tool,

FIG. 2 a cylinder liner with contouring in a cylinder block housing,

FIG. 3 a cylinder liner with sinustoulouse contouring,

FIG. 4 a cylinder liner with castelated contouring,

FIG. 5 a cylinder liner with sinustoulous and two maximum,

FIG. 6 a cylinder liner with sinustouslous contouring and one maximumand

FIG. 7 a separating process of two cylinder lines from one tube.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 an inventive cylinder liner 2 is shown, which is seated on acenter sleeve 4 of a not shown pressure die casting tool for a cylinderblock. The cylinder liner 2 (liner) exhibits on one end facing the crankspace 14 a contouring 6. The contouring 6 is here by way of exampleapproximately sinus shaped and exhibits multiple recesses 10 withrespectively one minimum 11 and likewise many rises 8 (maximum). Theliner is comprised of one super eutetic aluminum-silcon alloy.

By the maxima the liner 2 is supported on one edge 12 of the centersleeve 4. The edge 12 of the center sleeve 4 forms in the cylinder blockthe crank space 14. The oppositely lying side of the sleeve 2 isbordered by a cylinder head separating surface 16.

A maxima 8 is preferably so oriented relative to the center sleeve 4,that it substantially shields the sleeve 2 from the aluminum flow duringthe pressure casting. Thereby the casting behind the sleeve, that is apenetration of molten aluminum between liner and center sleeve isreduced.

In a cast in state, as shown in FIG. 2, the recesses 10 are filled withthe material of the cylinder block (casting). This material is comprisedof a conventional casting alloy, for example AlSi9Cu3.

A lower edge 19 of the sleeve 2 lies—with the exception of the maxima8—on the casting material. A seating of the sleeve in the direction ofthe crank space 14 is thereby prevented. Further it is therebyprevented, that by a possible existing gap between the sleeve 2 and thecasting 18 (not shown) cooling fluid can enter into the oil space.

By the line 17 the bottom dead center or direction changing point of alower piston ring of a not shown cylinder is marked. In useful mannerthe minima 11 of the contouring 6 is continued to this line 17. A deepercontouring is fundamentally possible, would however negatively impactthe tribulogical characteristics of the cylinder contact surfaces 15 andpossibly lead to increased friction wear. The recesses are between 10 mmand 30 mm, preferably between 15 mm and 25 mm.

The cylinder contact surfaces are formed above line 17 by the sleeve 2and below the line 17 of equal parts of sleeve 2 and casting material18.

In the FIGS. 3 through 6 examples for the contouring of a cylindersleeve are illustrated. Basically the contouring can take any desiredshaped, taking into consideration an optimal material savings, however aperiodic and symmetric contouring is desirable.

In FIG. 3 a sinus shaped contouring 6-3 of the sleeve 2-3 with eightmaxima 8-3 and eight minima 11-3 is shown. In FIG. 4 the contouring 6-4of the sleeve 2-4 is shown castellated with seven maxima 8-4 and sevenminima 11-4. (The second number of the reference number represents thecorresponding figure).

The number of the maxima can also be reduced, for example to two maxima8-5 in FIG. 5 and two one maxima 8-6 in FIG. 6. As contouring it islikewise conceivable, however not shown here, would be a zigzag pattern,a trapezoid pattern or other curve shapes.

In the following example a process for producing an inventive cylinderliner is described. From a tube 20, which is comprised of a roundkneaded or worked super eutetic Al—Si-alloy, a contouring 6 shown inFIG. 7 is cut out by a cutting tool 22. For this the cutting tool 22 ismoved axially relative to the tube 20, wherein this movement issuperimposed over a rotational movement of the tube. The control of themovements occurs centrally and is coordinated based upon the contour tobe produced.

At the same time as the cutting process an application of force F canoccur in the axially direction. Beginning with the cut, which isintroduced by the cutting tool 22, there occurs by the force F aso-called cracking along the contouring 6. The process is referred to asstamp cracking. One advantage of this process is comprised therein, thatno sawdust is lost, whereby again material can be saved.

The cutting 22 is moved according to the above described process alongcontour 6-5. This is used essentially as an example and corresponds tothe contouring 6 shown in FIG. 5. Following the separating process twoidentical sleeves 2 and 3 remain.

A perpendicular cut 23 following the two sleeves can occur but aconventional saw cut or by a so-called roll separation.

Processes with likewise low sawdust, which is employable analogous tothe process according to FIG. 7, include laser cutting, water jetcutting or precision cutting. In preferred manner the cutting occurswith avoidance of formation of a burr from inside towards outside. Inthe case of using laser welding a burr formation is easier to avoid. Dueto the complexity and expense of the apparatus the laser welding couldalso occur from outside.

If for technical reasons a sawing of the sleeves is desired, then thisis possible with a contouring according to FIG. 6.

For the inventive sleeve basically all tribulogical suitable materialscan be employed. In most cases a super eutetic Al—Si-alloy, preferablyalloys with a Si component of between 15% and 25%, as well as alloysbased on iron. In particular in the case of sleeves based on iron thematerial saving supplementally means also a weight saving.

1. A cylinder sleeve for a cylinder crank case, wherein the cylindersleeve (2) includes on one end (5) a contouring (6) having multiplerecesses (10), wherein at least one highest rise (8) of the contouring(6) supports the cylinder sleeve (2) in a pressure injection castingtool against a center sleeve (4).
 2. The cylinder sleeve according toclaim 1, wherein the contouring (6) of the cylinder sleeve (2)corresponds to the negative shape of a contouring of a correspondingcylinder sleeve (3).
 3. The cylinder sleeve according to claim 2,wherein the contouring (6) of the cylinder sleeve (2) exhibits a phasedisplaced periodic symmetry with the contouring (7) of the correspondingcylinder sleeve (3).
 4. The cylinder sleeve according to claim 1,wherein a deepest recess (11) of the cylinder sleeve (2) extends to thelower bottom dead center (11) of a lower most piston ring.
 5. A processfor producing a cylinder sleeve for a cylinder crank case, comprising:dividing out multiple sleeves (2, 3) from a tube (20), wherein thedividing step includes cutting a contouring (6) by using a cutting tool(22), wherein the cutting tool (22) moves axially relative to the tube(20) while the tube (20) moves circumferentially, wherein the cylindersleeve (2) includes on one end (5) a contouring (6), wherein at leastone highest rise (3) of the contouring (6) supports the cylinder sleeve(2) in a pressure injection casting tool against a center sleeve (4). 6.The process according to claim 5, wherein the cutting tool (22) is movedin the inside of the pipe (20) and the cutting process occurs frominside towards outside.
 7. The process according to claim 5, wherein thecutting process is carried out by water jet cutting, by laser cutting,by roll separation or precision cutting or stamping.
 8. The processaccording to claim 5, wherein during the cutting process a force (F) isapplied against the pipe in both axial directions.